1. Technical Field of the Invention
The present invention relates to an electro-optical device, an inspection method for the same, and electronic equipment.
2. Description of the Related Art
As is well known, liquid crystal apparatuses are extensively used as the display units in a variety of electronic equipment, such as cellular telephones. Such a liquid crystal apparatus has a pair of substrates attached to each other through the intermediary of a sealing member, liquid crystal supported between the two substrates, and a plurality of electrodes for applying a voltage to the liquid crystal. More specifically, in a typical configuration, a drive signal output from a driver IC mounted on a substrate or a flexible substrate or the like is supplied to each electrode via wires formed on the substrate.
In a process for manufacturing such a liquid crystal apparatus, a so-called lighting inspection is generally performed. In the lighting inspection, it is determined whether all pixels normally light. To perform the lighting inspection, first, a plurality of inspection terminals provided on an inspection apparatus are brought into contact with the wires formed on a substrate. Then, predetermined drive signals are supplied from the inspection terminals to a plurality of electrodes via the wires. And an image displayed as a result is observed visually or by a CCD (Charge Coupled Device) camera so as to determine whether all pixels normally light.
However, in the case that the intervals among the wires formed on the substrate are small, it is extremely difficult to accurately bring respective inspection terminals into contact with desired wires. More specifically, in the case that the interval between adjoining wires is small, it is difficult to have one inspection terminal in contact only with a single wire. This results in undesirable contact of the inspection terminal with two adjoining wires, thereby preventing accurate inspection from being accomplished.
Furthermore, increasing the number of electrodes to achieve a higher display definition automatically requires more wires. In this case, it is necessary to reduce an interval between adjoining wires on a substrate. Accordingly, the problem described above becomes more marked. When COG (Chip On Glass) technology is used to mount a driver IC on a substrate, the wires on a projecting region must be concentrated in a region where the driver IC is to be mounted, and the intervals among the wires are reduced in the vicinity of the region. Hence, the problem described above exists in this case also. These problems will arise also in another electro-optical device, such as an EL apparatus employing an EL (Electro-Luminescence) layer as its electro-optical material.
The present invention has been made in view of the situations described above, and it is a feature of the present invention to provide an inspection method for an electro-optical device that permits accurate inspection even in the case that intervals among wires formed on a substrate are small, an electro-optical device for which the inspection method is used, and electronic equipment employing the electro-optical device.
To solve the problems described above, an electro-optical device in accordance with the present invention is equipped with a substrate holding an electro-optical material, and a plurality of wires that have routing wire portions formed in a region other than a region opposing the electro-optical material in the substrate, wherein a routing wire portion of each of the wires has a first portion and a second portion that has a width smaller than that of the first portion. In other words, the routing wire portion of each of the wires has the first portion and the second portion, and the intervals between adjoining routing wire portions at the second portions are larger than the intervals at the first portions.
Generally, in the inspection process for an electro-optical device, it is necessary to have inspection terminals in contact with wires exposed on a substrate (i.e., the routing wire portions). However, if the intervals among the wires are extremely small, there may be an inconvenience, for example, in that one inspection terminal undesirably comes in contact with two wires, making it difficult to accomplish accurate inspection. According to the electro-optical device in accordance with the present invention, the width of the second portion in the routing wire portion is smaller than the width of the first portion. In other words, the interval between adjoining wires at the second portions is larger than the interval at the first portions. Hence, by bringing the inspection terminal into contact with the second portion, it will be possible to avoid a situation that the inspection terminal contacts another wire even in the case that the inspection terminal to be in contact only with one of the wires is slightly shifted. Therefore, according to the present invention, even in the case that the intervals among the wires formed on the substrate (to be more accurate, the intervals at the first portions) are extremely small, the inspection using the inspection terminals can be accurately performed.
To implement such an action, it is alternatively conceivable, for example, to reduce the width of the entire routing wire portion. However, this configuration would cause a problem of an increased wire resistance or a problem in that the wires are easily broken. According to the present invention, the width of only a part (the second portion) of the routing wire portion is reduced, thus reducing the occurrence of the above problems.
The electro-optical device described above is preferably provided with a driver IC that is mounted in a region other than a region opposing the electro-optical material in the substrate and that supplies output signals to the wires. Thus, in the case that the driver IC is mounted on a substrate by using the COG technology, many wires must be concentrated in the region where the driver IC is mounted, thereby making it necessary to reduce the intervals among the wires. Therefore, a particularly marked advantage can be obtained by applying the present invention, which realizes accurate inspection even when the intervals among wires are small, to an electro-optical device with a driver IC mounted on a substrate thereof.
Also desirable is a configuration in which pixels constructed by a plurality of sub-pixels respectively corresponding to different colors and color filters of the colors corresponding to the respective sub-pixels are provided. In an electro-optical device that enables full-color display, a plurality of sub-pixels corresponding to different colors make up one pixel. Hence, the electro-optical device that enables full-color display has more wires than a monochromic display electro-optical device that has the same number of pixels, so that the intervals among the wires need to be reduced. However, the present invention enables accurate inspection even in the case that the intervals among the wires are small as mentioned above.
In an electro-optical device equipped with a plurality of first electrodes and a plurality of second electrodes that are located on the other side of the first electrodes, sandwiching the electro-optical material therebetween and that extend in a direction for intersecting with the first electrodes, the wires may connect to either the first electrodes or the second electrodes, whichever have more electrodes. In other words, usually, wires connecting to many electrodes make it difficult to accomplish accurate inspection because of their small intervals. However, providing the wires with the first portions and the second portions allows accurate inspection to be implemented.
In the electro-optical device according to the present invention, preferably, the wire has a first layer and a second layer that has a resistance value lower than that of the first layer, and the second layer is formed to correspond at least to the second portion in the wire. In the case that the width of the second portion is set smaller than that of the first portion, the resistance value in the second portion will be conceivably higher. However, constructing the second portion from the first layer and the second layer that has a lower resistance value than the first layer makes it possible to control a rise in the resistance value attributable to a smaller width. To be more specific, it is conceivable to form the first layer from a metal oxide film and to form the second layer from a metal film. Furthermore, in an electro-optical device equipped with an electrode that is formed on the substrate and applies a voltage to the electro-optical material, it is desirable to form the first layer made of the metal oxide film by using the same layer as the electrode. This makes it possible to simplify the manufacturing process and reduce manufacturing cost, as compared with a case that the first layer and the electrode are formed in separate steps.
When a wire having a first layer and a second layer is adopted, it is preferable to avoid for forming the second layer the portion where the wire and the driver IC are connected. In the case that the second layer is formed from, for example, silver or an alloy containing silver as a primary component, a problem may arise in that the second layer easily comes off the substrate when subjected to an external force. However, by avoiding for forming the second layer the portion where the wire and the driver IC are connected, it will be possible to prevent a force from the driver IC from affecting the second layer, thereby making it possible to prevent the second layer from coming off the substrate.
It is also preferable to substantially align the second portions for the plurality of wires. This is advantageous in that a plurality of inspection terminals to be brought into contact with the second portions of the individual electrodes are arranged substantially in a row in an inspecting apparatus used for the lighting inspection, thus achieving a simpler configuration.
The present invention can be applied to a liquid crystal apparatus having liquid crystal, which is the electro-optical material, supported between the substrate and another substrate attached to each other through the intermediary of a sealing member. In the electro-optical device to which the present invention is applied, in the case that the wire is formed to have a first layer and a second layer having a resistance value lower than that of the first layer, it is desirable to form the second layer so as to correspond to at least the second portion in the wire and to avoid the region where the sealing member is formed in the substrate. This makes it possible to control a rise in the resistance value caused by reducing the width of the wire at the second portion. Moreover, in the case that the second layer is formed of, for example, a silver alloy, a problem may arise in that the second layer easily comes off a substrate. However, by avoiding for forming the second layer the region, where the sealing member has been formed, it will be possible to prevent a force from the sealing member from affecting the second layer, thus making it possible to prevent the second layer from coming off the substrate.
The present invention can be applied also to a variety of electro-optical devices, such as an EL apparatus employing an EL luminescent layer as the electro-optical material, in addition to liquid crystal apparatuses.
Furthermore, to solve the problems, electronic equipment in accordance with the present invention is provided with the electro-optical device described above as a display unit. As described above, the electro-optical device in accordance with the present invention allows accurate lighting inspection even in the case of the small intervals among wires, so that the possibility of the electro-optical device incurring display failure can be reduced in the electronic equipment incorporating the electro-optical device. The advantages provided by the present invention will be particularly marked in a configuration wherein a driver IC is mounted on a substrate or a configuration wherein the second portions are substantially aligned for a plurality of wires.
Furthermore, to solve the problems described above, there is provided an inspection method for an electro-optical device equipped with a substrate holding an electro-optical material, and a plurality of wires that have routing wire portions formed in a region other than the region opposing the electro-optical material in the substrate, wherein the routing wire portion of each of the wires has a first portion and a second portion having a width smaller than that of the first portion, the inspection method including a step for bringing an inspection terminal into contact with the second portion of the routing wire portion in each of the wires, a step for supplying a predetermined drive signal to the wire via the inspection terminal, and a step for determining whether the electro-optical device is good or bad on the basis of an image displayed by supplying the drive signal.
In an electro-optical device to which the inspection method is applied, even in the case that the intervals among wires have to be made extremely small, relatively large intervals can be secured among the wires at the second portions. Therefore, even when the inspection terminal brought into contact with each wire is slightly shifted from the wire to contact with, it will be possible to avoid a situation where the inspection terminal contacts another adjacent wire. Therefore, even in the case of the extremely small intervals among wires, accurate inspection can be performed.
In the step for bringing an inspection terminal into contact with the routing wire portion in the inspection method, it is desirable to bring the plurality of inspection terminals into contact with the second portions of the wires at a time. This makes it possible to determine the presence of disconnection or short circuit in many wires at the same time, permitting highly efficient inspection to be performed. In the step for bringing the inspection terminals into contact with the routing wire portions, it is desirable to abut the inspection terminals substantially shaped like flat plates against the wires to flex the inspection terminals thereby to cause the inspection terminals and the wires to be in surface contact with each other. Bringing the inspection terminals and the second portions into surface contact in this manner allows predetermined drive signals to be securely applied to the wires, further improving inspection accuracy to be achieved.